Swan Range Passive

INTRODUCTION

PROJECT DESCRIPTION

The Swan Range Passive is an accessory family home located in Flathead County, Montana, designed to meet the needs of a multi-generational family. The project's primary goal was to provide needed lodging for the growing family, offering both space and comfort while emphasizing energy efficiency, durability, and accessibility. The design was intended to be a modest and simple addition to the main house, intended as a common space for the entire family to gather and enjoy together.

The family had outgrown their existing lake house and needed more room. They envisioned the new home as a functional, healthy, and worry-free space that could accommodate their whole family. Key design goals included creating an inviting family home with an accommodating floor plan that would be both low maintenance and inspiring. Indoor air quality, materials and layout were all reviewed to be safe and ecologically sensible.

The project also aimed to implement a better solution to the solar overheating issues experienced in the main house. The main house, with large windows facing the lake, faced a significant challenge in the summer, as the sun reflected off the water and caused the house to overheat. This led to an overworked air conditioning system, indoor glare at key sun angles, and in general a less livable home. The new home sought to address this with improved passive design strategies to prevent the same issues.

SCOPE AND DESIGN FEATURES

The family chose the same architect who designed their main house, leveraging the architect’s familiarity with the site conditions. Construction began during the pandemic, a time of significant challenges due to labor shortages and volatile material pricing. Despite these challenges, the project stayed on track by partnering with a regional prefab company experienced in panelized building enclosures, which helped stabilize both the budget and timeline.

The home spans 2,500 square feet of conditioned space, including four bedrooms and four bathrooms. The layout consists of a primary suite, three additional bedrooms sharing two bathrooms (one hall bath and one dorm-style bath), and a spacious mudroom. The main floor houses an open, inviting gathering space that connects to both the south yard and the beach, providing beautiful views of the lake. A semi-conditioned summer game room is located below the main house, at the lake level. The design also emphasizes energy efficiency, with the lower level thermally isolated from the super-efficient envelope above.

DURATION AND COSTS

Construction lasted around two years, completed in 2024, with the final build cost totaling approximately $400 per square foot.

CONCLUSION

Swan Range Passive represents a successful approach to multi-generational familial living in a beautiful and challenging environment that is characterized by extremely cold, low-light winters and fairly warm, long summer days. By focusing on energy efficiency, simplicity, and durability, the family created a sustainable and comfortable space that supports their shared time together while addressing the unique climate challenges of the area.

DESIGN OBJECTIVES

SUSTAINABILITY

The Swan Range Passive home was strategically designed to maximize both energy efficiency and environmental performance. Located on the eastern end of a lake in Montana, the site’s unique topography sloped down towards the shoreline, offering expansive views of the lake and surrounding nature. The design capitalized on these views while addressing environmental and energy concerns.

Instead of orienting the building to face the lake with large windows (a typical approach), the design prioritized passive solar strategies to minimize overheating during the summer months while maximizing winter solar gain. The architects carefully analyzed the site, adjusting the home’s footprint and rotation to optimize solar access and views. This approach not only provided ample sunlight to warm the home during cold months but also avoided excessive heat gain in the afternoons, preventing the need for excessive cooling.

To ensure a low-carbon footprint and enhanced energy performance, the building features a highly insulated envelope that contributes to its potential for Passive House certification. The design also integrates strategic shading, reducing energy consumption while enhancing occupant comfort.

ACCESSIBILITY

Accessibility was carefully considered in the design of Swan Range Passive to ensure that it meets the needs of various user groups. The home was designed with the understanding that it will be used not only by the owners from time to time, but also rented long-term to local families. This required providing an environment that was easy to navigate for individuals of all ages and abilities.

A gentle and wide path leads from the house to the lake, making it accessible for those using wheelchairs or other forms of mobility assistance. For visitors who may not be able to make the descent to the lake, the main floor of the house was designed with strong visual connections to the outdoors. The large windows provide views of the south yard and the beach, ensuring that everyone can enjoy the surrounding natural beauty without needing to physically access every outdoor space.

AESTHETICS

The aesthetic design of the Swan Range Passive home balances the natural beauty of its lakeside setting with a pragmatic approach to energy efficiency. The simple gable roof and corrugated metal siding reflect the utilitarian yet enduring nature of traditional Montana structures, which are designed to withstand the harsh climate with minimal maintenance.

The exterior details were intentionally kept simple, allowing the building to blend with its environment while prioritizing long-term durability. The focus on efficiency also extended to the selection of materials, with higher-end finishes reserved for the main gathering space, where the family would spend most of their time. Overall, the home’s form and materials are both functional and aesthetic, resonating with the owners' goals of creating a low-maintenance yet beautiful gathering space.

COST-EFFECTIVENESS

The project’s cost-effectiveness was achieved through thoughtful decisions during the design and construction phases. While the upfront investment in energy-efficient systems and thicker walls was higher, these costs are expected to pay off within a relatively short time, making the home’s long-term operation significantly more affordable.

The use of a regional pre-fabrication company reduced construction time and labor costs, especially during a period of labor shortages and material price volatility caused by the pandemic. By utilizing prefabricated components and local suppliers, the project was able to maintain both budget stability and quality, despite these challenges. This offsite construction method also allowed for more precise scheduling and ensured that assembly was carried out under optimal weather conditions.

Exposure to the harsh Montana winter was minimized by assembling key components of the superstructure in an indoor factory. The same fabricators who assembled the components also collaborated with the GC on site to expedite the dry-in process which was completed in just over two weeks. Subsequently, finishes, both interior and exterior could be installed when weather was more predictable and materials were at a more common temperature range (not negative 10F).

FUNCTIONAL/OPERATIONAL

The design of the Swan Range Passive home is centered around functionality, focusing on a simple, efficient layout that aligns with the client’s desire for low maintenance and ease of operation. The spatial layout was designed to prioritize comfort and energy efficiency by taking full advantage of solar orientation. Active living spaces were placed to the south to maximize natural light, while less frequently used areas were positioned on the north side to reduce energy demands.

The building’s robust waterproofing system, integrated with vapor control and an Energy Recovery Ventilator (ERV), ensures a dry, comfortable interior while extending the lifespan of building components. The design's simplicity reduces the need for intensive maintenance, while the ERV ensures air quality by regularly exchanging indoor air, which is particularly important in areas with extreme weather conditions such as fire and smoke risks.

ENERGY CERTIFICATIONS

Passive House Certified by Phius

U.S. DOE Zero Energy Ready Home Status

U.S. EPA Indoor airPLUS label

EPA ENERGY STAR Certification

RESNET HERS Index Score